The objective of this work for the coming year will be to further characterize the T1-specific transcripts made after infection of two different host cell populations: ordinary E. coli, and E. coli that are previously infected with phage lambda and allowed a short period of incubation for the expression of lambda's N gene. Recent work has identified three major classes of T1-specific transcripts made in ordinary host cells with respect to the time after infection at which they are made and to the intensity of their transcription. We plan to characterize the same classes as they appear in lambda-preinfected cells, and then determine the molecular size of the transcripts produced for each class in each kind of cells.